Multi-channel lighting fixture having multiple light-emitting diode drivers

ABSTRACT

A lighting control system for controlling a cumulative light emitted by a lighting fixture having a plurality of LED light sources may comprise a plurality of LED drivers adapted to be coupled to a respective one of the LED light sources and configured to control an intensity of the respective LED light source, and a controller configured to transmit a single digital message for controlling the cumulative light emitted by the lighting fixture. Each of the plurality of LED drivers is configured to adjust the intensity of the respective LED light source to a preset intensity in response to the single digital message transmitted by the controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/572,503 filed Sep. 16, 2019 (now U.S. Pat. No. 10,736,193, issuedAug. 4, 2020), which is a continuation of U.S. patent application Ser.No. 16/105,656, filed on Aug. 20, 2018 (now U.S. Pat. No. 10,420,187,issued Sep. 17, 2019), which is a continuation of U.S. patentapplication Ser. No. 15/869,653, filed on Jan. 12, 2018 (now U.S. Pat.No. 10,057,958, issued Aug. 21, 2018), which is a continuation of U.S.patent application Ser. No. 14/975,070, filed Dec. 18, 2015 (now U.S.Pat. No. 9,888,543, issued on Feb. 6, 2018), which claims the benefit ofU.S. Provisional Patent Application Ser. No. 62/094,703, filed Dec. 19,2014, the entire disclosures of which are incorporated by referenceherein.

BACKGROUND

Traditional sources of light such as the sun (and later incandescentlights) may exhibit the characteristics of a black body radiator. Suchlight sources typically emit a relatively continuous-spectrum of light,and the continuous emissions range the entire bandwidth of the visiblelight spectrum (e.g., light with wavelengths between approximately 390nanometers (nm) and 700 nm). The human eye has grown accustomed tooperating in the presence of black body radiators and has evolved to beable to distinguish a large variety of colors when emissions from ablack body radiator are reflected off of an object of interest.

Further, the frequency or wavelength of the continuous light spectrumemitted by a black body radiator may be dependent on the temperature ofthe black body radiator. Plank's law states that a black body radiatorin thermal equilibrium will emit a continuous-spectrum of light that isdependent on the equilibrium temperature of the black body. FIG. 1illustrates the black body temperature curve (e.g., color map) accordingto Plank's law. As shown in FIG. 1, as the temperature of the black bodyradiator increases, the frequency of the peak of the emitted spectrumshifts to higher frequencies. At room temperature (e.g., roughly 300Kelvin (K)), the frequency peak is typically within the infrared portionof the spectrum and thus is imperceptible to the human eye. However,when the temperature is increased to approximately 700-750 K, theblackbody radiator will begin to emit light in the visible range of theelectromagnetic spectrum.

Typically, as the temperature of the black body radiator decreases, thewavelength of the emitted light increases and the frequency decreases,such that the emitted light appears redder. As the temperatureincreases, the peak of the emitted spectrum become bluer or decreases inwavelength (e.g., increases in frequency). For black body radiators,this relationship between temperature and wavelength/frequency of theemitted light is inseparable—higher temperature radiators appear bluerand lower temperature radiators appear redder.

Thus, various wavelengths/frequencies of the visible light spectrum maybe associated with a given color temperature of a black body radiator.The color temperature of a light source may refer to the temperature ofan ideal black body radiator that radiates light of comparable hue tothat of the light source. For example, candlelight, tungsten light(e.g., from an incandescent bulb), early sunrise, and/or household lightbulbs may appear to have relatively low color temperatures, for exampleon the range of 1,000-3,000 K. Noon daylight, direct sun (e.g., sunlightabove the atmosphere), and/or electronic flash bulbs may appear to havecolor temperature values on the order of 4,000-5,000 K and may have agreenish blue hue. An overcast day may appear to have a colortemperature of approximately 7,000 K and may be even bluer than noondaylight. North light may be bluer still, appearing to have a colortemperature on the range of 10,000 K. Color temperatures over 5,000 Kare often referred to as cool colors (e.g., bluish white to deep blue),while lower color temperatures (e.g., 2,700-3,000 K) are often referredto as warm colors (e.g., red through yellowish white).

Incandescent and halogen lamps typically act as black body radiators.For example, a current is passed through a wire (e.g., a filament),causing the wire to increase in temperature. When the wire reaches acritical temperature, it begins to radiate light in the visiblespectrum. The color temperature of the radiated light is dictated byPlank's law. When an incandescent or halogen light is dimmed, thetemperature (and color temperature) is decreased, meaning that theemitter light becomes redder (e.g., higher wavelength, lower frequency).Thus, humans are accustomed to dimmed lights having a redder hue.

Recently, non-incandescent light sources such as fluorescent lights(e.g., compact fluorescent lights or CFLs) and light emitting diodes(LEDs) have become more widely available due to their relative powersavings as compared to traditional incandescent lamps. Typically lightfrom CFLs or LEDs does not exhibit the properties of a black bodyradiator. Instead, the emitted light is often more discrete in naturedue to the differing mechanisms by which CFLs and/or LEDs generate lightas compared to an incandescent or Halogen light bulbs. Sincefluorescents and LEDs do not emit relatively constant amounts of lightacross the visible light spectrum (e.g., instead having peakedintensities at one or more discrete points within the visible spectrum),fluorescents and LEDs are often referred to as discrete-spectrum lightsources.

The wavelength/frequency profile of a light source may be dependent onthe device or technique used to generate the light. For example, lightfrom fluorescent lamps is produced by electrically exciting mercurywithin a glass tube. The applied voltage causes the mercury to become aplasma that emits light in the ultraviolet (UV) frequency range.Typically, the glass tube is coated with a phosphorus-based materialthat absorbs the radiated UV light and then emits light in the visiblefrequency range. The wavelength shift from UV to the visible range isreferred to as Stokes shift. Depending on the properties of thephosphorus-based material, the wavelength/frequency of the light emittedmay be at different points within the visible spectrum. A CFL lamp mayemit a discrete spectrum of light, which may be characterized by one ormore bursts of emissions at discrete frequencies/wavelengths.

Light from LEDs is produced due to the physical properties of asemiconducting material. For example, when a voltage is applied across asemiconductor junction that has different levels of electron dopingacross the boundary, an electric current is induced. When an electronfrom one side of the device recombines with an electron hole on theother, a photon is emitted. Depending on the semiconductor design, thephotons may be emitted at various wavelengths/frequencies within thevisible light spectrum. Like fluorescents, Stokes shift may cause thefrequency of the emitted photons to be lowered to achieve a desiredlight frequency output. Like the emissions from the fluorescent lamp,the LED light may also be relatively discrete in nature (e.g., adiscrete spectrum).

When discrete-spectrum light sources are dimmed, their color temperaturemay change in a different manner as black body radiators. For example,when incandescents and halogens are dimmed, their temperature isdecreased and the emitted light transitions to a lower color temperaturevalue (e.g., becomes redder) according to Plank's law. However, sincediscrete-spectrum light sources are not black body radiators, Plank'slaw may not apply. For example, both fluorescent lamps and LEDs maymaintain a relatively constant color temperature even in the presence ofdimming (e.g., and may actually become slightly bluer or higherfrequency as they are dimmed). Such an effect may be unnatural to thehuman eye, which may expect the color temperature to shift to a reddertemperature as the light dims. Moreover, when discrete-spectrum lightsources are placed in the vicinity of other light sources, for examplesources of light whose color temperature may change over time, thediscrete-spectrum light sources can appear unnatural or distracting.

SUMMARY

As described herein, a lighting control system for controlling acumulative light emitted by a lighting fixture having a plurality of LEDlight sources may comprise a plurality of LED drivers adapted to becoupled to a respective one of the LED light sources and configured tocontrol an intensity of the respective LED light source, and acontroller configured to transmit a single digital message forcontrolling the cumulative light emitted by the lighting fixture. Eachof the plurality of LED drivers is configured to adjust the intensity ofthe respective LED light source to a preset intensity in response to thesingle digital message transmitted by the controller.

In addition, a controller for controlling a cumulative light emitted bya lighting fixture is also described herein. The lighting fixture mayinclude a plurality of LED light sources and a plurality of respectiveLED drivers. The controller may comprise a communication circuitconfigured to transmit digital messages via a digital communicationlink, and a control circuit configured to cause the communicationcircuit to transmit a single digital message on the communication link.The single digital message may include a command for causing theplurality of LED drivers to adjust the intensity of the respective LEDlight sources to respective preset intensities to control the cumulativelight emitted by the lighting fixture.

A control module for controlling a cumulative light emitted by alighting fixture may comprise a first communication circuit configuredto receive a digital message via a digital communication link, a secondcommunication circuit adapted to be electrically coupled to a pluralityof LED drivers for controlling respective LED light sources, a memoryconfigured to store a light engine defining preset intensities for theLED light sources, and a control circuit configured to control theplurality of LED drivers to adjust the intensity of the respective LEDlight sources to respective preset intensities to control the cumulativelight emitted by the lighting fixture in response to a single digitalmessage via the digital communication link.

A master LED driver for controlling a cumulative light emitted by alighting fixture may comprise a load regulation circuit adapted to becoupled to a first LED light source and configured to control theintensity of the first LED light source, a first communication circuitconfigured to receive a digital message via a digital communicationlink, a second communication circuit adapted to be electrically coupledto a slave LED driver for controlling a second LED light source, and acontrol circuit configured to control the load regulation circuit toadjust the intensity of the first LED light source and to control theslave LED driver to adjust the intensity of the second LED light sourceto control the cumulative light emitted by the lighting fixture inresponse to a single digital message via the digital communication link.

Further, a method of configuring at least first and second LED driversto be installed in a single lighting fixture is described herein. Thelighting fixture may include at least first and second LED light sourcesadapted to be controlled by the respective LED drivers to control acumulative light emitted by the lighting fixture. The method maycomprise: storing a first light engine in a first memory of the firstLED driver, the first light engine defining preset intensities for thefirst LED light source; and storing a second light engine in a secondmemory of the second LED driver, the second light engine defining presetintensities for the second LED light source. The first and second LEDdrivers may be configured to control the cumulative light emitted by thelighting fixture in response to a single received digital message byadjusting the intensities of the respective LED light sources torespective preset intensities determined from the respective lightengines. The first and second LED light sources comprise different colorLED light sources and the first and second light engines compriserespective first and second color engines. The method may also compriseinstalling in the first and second LED light sources and first andsecond LED drivers in the lighting fixture, and adjusting the first andsecond color engines to calibrate a color (e.g., a color temperature) ofthe cumulative light emitted by the lighting fixture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example of the black body color temperature curveaccording to Plank's law.

FIGS. 2-4 are simple diagrams of example load control systems, eachhaving a plurality of lighting fixtures (e.g., multiple-driver lightingfixtures) for illuminating a space.

FIGS. 5A and 5B are simplified block diagrams of load regulationdevices, such as LED drivers for controlling the intensities of LEDlight sources in a multiple-driver lighting fixture.

FIG. 6 is a simplified block diagram of an example control module forcontrolling LED drivers in a multiple-driver lighting fixture.

FIG. 7 is a simplified flowchart of an example configuration procedurefor configuring a multiple-driver lighting fixture having multiple LEDlight sources and respective LED drivers.

FIG. 8 is a simplified flowchart of an example setup procedure forprogramming the operation of a load control system havingmultiple-driver lighting fixtures.

FIG. 9 is a simplified flowchart of an example message processingprocedure that may be executed by an LED driver of a multiple-driverlighting fixture.

FIG. 10 is a simplified flowchart of an example message processingprocedure that may be executed by a control module of a multiple-driverlighting fixture.

FIG. 11 is a simplified flowchart of an example message processingprocedure that may be executed by a master LED driver of amultiple-driver lighting fixture.

FIG. 12 is a block diagram of an example system controller.

FIG. 13 is a block diagram of an example input device.

DETAILED DESCRIPTION

The various systems and methods described herein for shifting a lightsource to a higher wavelength/lower frequency. Such systems and methodsmay describe the changing the effective or composite color (e.g., colortemperature) of a light source to a lower color (e.g., colortemperature). The effective or composite color (e.g., color temperature)of a light source may be changed to a higher color (e.g., colortemperature) by shifting the light source to a lower wavelength/higherfrequency. Although color temperature may be described herein as anexample for adjusting the color of a light source, other parameters(e.g., hue, saturation, etc.) may be used to adjust colorcharacteristics of a light source.

There may be numerous ways for shifting the color (e.g., the colortemperature) of a discrete-spectrum light source. For example, two ormore discrete-spectrum light sources may be controlled to vary theeffective color temperature of a combined or composite light emittedfrom the two or more discrete-spectrum light sources (e.g., thecorrelated color temperature). A composite light or combined lightemitted from two or more light sources may include a mixed or jointemissions of light as seen from an observer at a distance away from thelight source. For example, the light sources may be included in a singlelight fixture, and to an observer in a room that includes the fixturethe composite light emitted by the two or more light sources may appearto be from as a single light source. The light fixture may or may notinclude a diffuser or other instrument that makes the composite lightemitted from the two or more discrete-spectrum light sources appear tobe emitted from a single light source.

Although a first light source may be included in a different lightingfixture than a second light source, the two light sources may be locatedsufficiently close together from the perspective of an observer thattheir composite emissions appear to be from a single light source. Therelative proximity of two or more light sources that emit composite orcombined light emissions may vary depending on the position or distanceof a desired target or observer of the composite light emissions. Forexample, the two or more light sources may be located relatively closetogether (e.g., in the same fixture) if the target or observer of thecomposite light is relatively close to the light sources (e.g., in thesame room). If the target or observer is farther away, the two or morelight sources may be separated by a relatively greater distance.

As noted above, the composite light may be the combined emissions of twoor more discrete-spectrum light sources. One or more discrete-spectrumlight sources may be used in combination with a continuous-spectrumlight source such as an incandescent or halogen lamp. The compositelight emitted from such a device may include the light emitted from thecontinuous-spectrum light source (e.g., and potentially multiplecontinuous-spectrum light sources) and the one or more discrete-spectrumlight sources. Various combinations of discrete-spectrum light sourcesand continuous-spectrum light sources may be utilized.

Multiple discrete-spectrum light sources may be used to achieve variouseffective colors (e.g., color temperatures). For example, if a firstdiscrete-spectrum light source has an effective color temperature in thered range (e.g., on the order of 1,000 to 2,000 K) and a seconddiscrete-spectrum light source has an effective color temperature in theblue range (e.g., on the order of 10,000 K), then the total combinedcolor temperature or composite color temperature of light emitted fromthe combination of the first discrete-spectrum light source and thesecond discrete-spectrum light source may be of greenish hue (e.g., onthe order of 4,000-5,000 K) due to the human eye's perception of thecomposite light emitted by the two light sources. By utilizing morediscrete-spectrum light sources emitting light associated with variouscolor temperature values, more exact color temperature control may beachieved.

A first discrete-spectrum light source may maintain a constant intensitylevel, and an intensity level of a second discrete-spectrum light sourcemay be varied (e.g., the intensity level may be increased, decreased,etc.). Increasing the intensity of the second discrete-spectrum lightsource may cause the composite color temperature (e.g., the correlatedcolor temperature) of the light sources to become closer to that of thesecond discrete spectrum light source. Decreasing the intensity of thesecond discrete-spectrum light source may cause the composite colortemperature (e.g., the correlated color temperature) of the lightsources to become closer to that of the first discrete-spectrum lightsource.

The intensity levels of discrete-spectrum light sources may be varied toachieve a desired color (e.g., a desired color temperature value) forthe composite emissions from the discrete-spectrum light sources. Asystem controller and/or the load control system that controls theintensity levels of the first and second discrete-spectrum lightsources, for example, may maintain a state table or other information insystem memory that associates a desired color for composite lightemissions with intensity levels of the first and second light sources.Thus, the controlling device may be able to determine appropriateintensity levels for each of a plurality of discrete-light sources basedon the desired color of the composite light emitted by the plurality ofdiscrete-spectrum light sources.

In addition to the desired color of the composite light being used toselect appropriate intensity levels of the discrete-spectrum lightsources, the overall or combined intensity of the light may be used toselect appropriate intensity levels for the underlying discreet-spectrumlight sources. For example, in a light fixture that utilizestwo-discrete spectrum light sources, a desired color temperature valuefor the composite light emitted by the light fixture may be achievedusing various combinations of intensity levels of the first and seconddiscrete-spectrum light sources. Although different combinations ofintensity levels for the first and second discrete-spectrum lightsources may be used to achieve approximately the same color temperaturevalue of the composite emissions, the different combinations may resultin different overall intensity levels of the composite light (e.g., theoverall composite intensity may be dimmer for a first combination andbrighter for a second combination). Thus, the system controller and/orthe load control system that controls the intensity levels of the firstand second discrete-spectrum light sources may determine the individualintensity levels of the first and second discrete-spectrum light sourcesbased on both the desired color temperature value of the composite lightand the desired overall intensity level of the composite light. Table 1illustrates an example state table that may be maintained in order todetermine appropriate intensity levels of the first and seconddiscrete-spectrum light sources based on a desired color temperaturevalue of the composite light and a desired overall intensity level ofthe composite light.

TABLE 1 Desired Color Desired Intensity Level Intensity TemperatureIntensity of First Level of Second Value of Level of Discrete- Discrete-Composite Composite Spectrum Light Spectrum Light Emissions (K)Emissions Source Source 8,000 L_(C1) L_(A1) L_(B1) 4,000 L_(C1) L_(A2)L_(B2) 2,000 L_(C1) L_(A3) L_(B3) 8,000 L_(C2) L_(A4) L_(B4) 4,000L_(C2) L_(A5) L_(B5) 2,000 L_(C2) L_(A6) L_(B6)

In the example shown in Table 1, if the desired color temperature ofemissions is approximately 8,000 K and the desired composite intensitylevel is L_(C1), the first discrete-spectrum light source may be set tointensity level L_(A1), and the second discrete-spectrum light sourcemay be set to intensity level L_(B)1. As an example, such a compositecolor temperature and composite intensity level may correspond to thefirst discrete-spectrum light source operating at full intensity (e.g.,L_(A1)=100%) and while the second-discrete spectrum light sourceoperates at half intensity (e.g., L_(B1)=50%). If the color temperatureis to be lowered to 4,000 K, but the overall composite intensity is toremain relatively constant, the first discrete-spectrum light source maybe set to intensity level L_(A2), and the second discrete-spectrum lightsource may be set to intensity level L_(B2). In some instances, such achange in color temperature may be achieved by varying the intensitylevel of a single discrete-spectrum light source of thediscrete-spectrum light sources. If the desired composite colortemperature is to remain constant at 8,000 K, but the overall compositeintensity level is to be changed (e.g., dimmed) to level L_(C2), thefirst discrete-spectrum light source may be set to intensity levelL_(A4), and the second discrete-spectrum light source may be set tointensity level L_(B4). For example, such a composite intensity levelL_(C2) at color temperature 8,000 K may correspond to the firstdiscrete-spectrum light source operating at half intensity (e.g.,L_(A4)=50%) and while the second discrete spectrum light source operatesat quarter intensity (e.g., L_(B4)=25%).

Although the example described with respect to Table 1 utilizes twodiscrete spectrum light sources, similar relationships may be determinedfor systems utilizing more than two discrete-spectrum light sources. Forexample, by utilizing more than two discrete-spectrum light sourceshigher degrees of granularity may be achieved for adjusting one or moreof the desired color temperature value of the composite emissions and/orthe desired intensity level of composite emissions. In addition to, orrather than, one or more discrete-spectrum light sources, one or morecontinuous-spectrum light sources may be used. When determiningappropriate intensity values for light sources that include at least onecontinuous-spectrum light source, Plank's law may be taken into accountfor the continuous-spectrum light sources, such that changes inintensity level may change the color temperature of the light emitted bythe continuous-spectrum light source. Such an effect may lead tonon-linear relationships between intensity levels of light sources andthe color temperature of the combined emissions and/or of the compositeintensity level of the emissions.

FIG. 2 is a simple diagram of an example load control system 200 havinga plurality of lighting fixtures 210, 220, 230 for illuminating a space.The lighting fixture 210 may comprise a single lighting load (e.g., anLED light source 212) and a load regulation device (e.g., an LED driver214) for controlling the LED light source 212. The lighting fixtures220, 230 may be multi-channel lighting fixtures having LED light sourcesthat have different operating characteristics (e.g., power rating, colortemperature, etc.) as described in greater detail herein.

Utilizing multiple-discrete spectrum light sources within a fixture maypresent many and various advantages over fixtures comprising a singlemulti-channel driver. Such advantages may include flexibility,robustness, as well as other advantages. For example, when utilizingmultiple-discrete spectrum light sources within a fixture, the number ofchannels to be used may be equivalent to the number of light sources(e.g., LED light sources) desired to be included in a fixture. This isin contrast to a single multi-channel driver, which may limit the numberof channels to be used to the number of channels on the multi-channeldriver. Utilizing multiple-discrete spectrum light sources within afixture may allow variations in the size, cost, and/or efficiency ofdrivers (e.g., LED drivers) in each fixture. These variations may beused to easily and/or cost-effectively design fixtures for differentneeds, and may provide an advantage over a fixture comprising a singlemulti-channel driver, as designing optimized multi-channel drivers forparticular installations may be impractical. Further, when utilizingmultiple-discrete spectrum light sources within a fixture, if one driver(e.g., LED driver) fails, light may continue to be output from thefixture (e.g., light may be output from light sources controlled byworking drivers within the fixture). This differs from when amulti-channel driver fails, e.g., because in such an example the entirefixture may discontinue outputting light altogether.

The LED driver 214 of the lighting fixture 210 may be coupled to a powersource, such as an alternating-current (AC) power source and/or adirect-current (DC) power source, and may be configured to control theamount of power delivered to the LED light source 212 to adjust theintensity of the LED light source. The LED driver 214 may be coupled toa digital communication link 204, such that LED driver 214 is able totransmit and receive digital messages via the communication link 204.The LED driver 214 may be configured to control the LED light source 212in response to digital messages received via the digital communicationlink 204. For example, the LED driver 214 may be configured to turn theLED light source 212 on and off and/or to adjust the intensity of theLED light source. The LED driver 214 may be configured to transmit adigital message including feedback information via the digitalcommunication link 204.

The lighting fixture 220 may comprise multiple lighting loads (e.g., LEDlight sources 222A, 222B) and respective load regulation devices (e.g.,LED drivers 224A, 224B). The LED drivers 224A, 224B may each be coupledto the digital communication link 204, such that each LED driver maytransmit and receive digital messages via the communication link. TheLED drivers 224A, 224B may be coupled to a power source, such as analternating-current (AC) power source and/or a direct-current (DC) powersource, and may be configured to control the amount of power deliveredto the respective LED light sources 222A, 222B to adjust the intensityof the LED light sources. The LED drivers 224A, 224B may be configuredto individually control the LED light sources 222A, 222B in response tothe digital messages received via the communication link 204. Thelighting fixture 220 may be, for example, a controllable-color lightingfixture (e.g., a controllable-color-temperature lighting fixture) wherethe LED light sources 222A, 222B are different color LED light sourcesand the light emitted by the LED light sources 222A, 222B may be mixedtogether to adjust the color (e.g., the color temperature) of thecumulative light emitted by the lighting fixture 220 (e.g., thecorrelated color temperature of the lighting fixture). For example, theLED light source 222A may be a white LED light source and the LED lightsource 222B may be a red LED light source. The LED drivers 224A, 224Bmay be configured to adjust the intensities of the white light emittedby the LED light source 222A and the red light emitted by the LED lightsource 222B, respectively, to control the color (e.g., the colortemperature) of the cumulative light emitted by the lighting fixture220, for example, in response to a single command (e.g., received in oneor more digital messages transmitted via the communication link 204).The single command may include an identification (e.g., address) of thelighting fixture 220 to be controlled.

The single command may include a desired color (e.g., a desired colortemperature) value of the composite light to be emitted from a lightingfixture. For example, the single command may include a desired color(e.g., a desired color temperature) value of the composite light beingemitted from the lighting fixture 220. The color temperature valueincluded in the single command may be a color temperature value alongthe black body temperature curve depicted in FIG. 1. The single commandmay include the desired overall and/or combined intensity level of thelighting fixture 220. The single command may include the desired overalland/or combined intensity level of the lighting fixture 220, inconjunction with a desired color (e.g., a desired color temperature).For example, the LED drivers 224A, 224B may be configured to control therespective LED light sources 222A, 222B to cause the lighting fixture220 to emit a desired combined color, color temperature, and/orintensity, based on the single command.

The single command may include a desired color trajectory value of thecomposite light to be emitted from the controlled lighting fixture 220.The desired color trajectory may be a desired color temperature for thelighting fixture 220 with respect to a desired total intensity for thecumulative light emitted by the lighting fixture 220 (e.g., when theintensity of the lighting fixture 220 is being adjusted as describedherein). For example, the single command may include the desired totalintensity for the lighting fixture 220 and the LED drivers 224A, 224Bmay be configured to control the respective LED light sources 222A, 222Bto cause the lighting fixture 220 to emit a color temperature as definedby the desired color trajectory. The color trajectory may correspond tothe color temperature of a specific lamp (e.g., an incandescent lamp, ahalogen lamp, or a fluorescent lamp), as the lamp is dimmed. Forexample, the color trajectory of the LED light fixture 220 may mimic anincandescent lamp when dimmed from a low-end intensity to a high-endintensity.

The single command may include a desired color map value of thecomposite light to be emitted from the controlled lighting fixture 220.For example, the single command may include the x and y coordinates of aspecific color on the color map depicted in FIG. 1, and may also includea z parameter corresponding to a desired intensity of the specificcolor. The single command may include hue and/or saturation parametersof a specific color to be emitted from the controlled lighting fixture220, and may also include a z parameter corresponding to a desiredintensity of the specific color. The single command may include red,green, and blue (RGB) parameters of a specific color to be emitted fromthe controlled lighting fixture 220, and may also include a z parametercorresponding to a desired intensity of the specific color.

The LED drivers 224A, 224B of the lighting fixture 220 may be assigned aunique light engine (e.g., a color engine) that defines the appropriateintensities to which to control the respective LED light source inresponse to commands received via the communication link 204. The LEDdrivers 224A, 224B may use the color engines during normal operation ofthe load control system 200 to determine the appropriate intensity tocontrol the respective LED light source to achieve a desired color,color temperature, color trajectory, color mapping, hue, saturation,and/or RGB colors for lighting fixture 220. For example, the colorengine may define a fixed color (e.g., a fixed color temperature) forthe lighting fixture 220.

The single command may include the desired intensity levels ofdiscrete-spectrum light sources, e.g., the single command may includethe desired intensity levels of each of the LED light source 222A and/orthe LED light source 222B. For example, the single command may instructLED driver 224A to provide an intensity level to LED light source 222A,and the single command may instruct LED light source 224B to provideanother intensity level to LED light source 222B. For example, the LEDdrivers 224A, 224B may be configured to receive a single command and/orcontrol the respective LED light sources 222A, 222B to become redder asthe total intensity of the cumulative light emitted by the lightingfixture 220 is decreased (e.g., dimmed).

The LED drivers 224A, 224B of the lighting fixture 220 may havedifferent power ratings. For example, the LED driver 224B for the LEDlight source 222B (e.g., the red LED light source) may have a smallerpower rating than the LED driver 224A for the LED light source 222A(e.g., the white LED light source), e.g., if a small shift towards aredder color (e.g., a redder color temperature) is desired when thetotal intensity of the cumulative light emitted by the lighting fixture220 is decreased. As an example, one LED driver (e.g., the LED driver224B) may be rated for 20 watts, and another LED driver (e.g., the LEDdriver 224A) may be optimized for 40 watts. Allowing the LED drivers224A, 224B of the lighting fixture 220 to have different power ratingsmay provide advantages. A combination of the LED drivers havingdifferent power ratings may be used, for example, to minimize cost andsize and maximum efficiencies of the LED drivers.

The lighting fixture 230 may comprise a plurality of lighting loads(e.g., LED light sources 232A, 232B, 232C) and respective loadregulation devices (e.g., LED drivers 234A, 234B, 234C). The LED drivers234A, 234B, 234C may each be coupled to the digital communication link204, such that each LED driver is able to transmit and receive digitalmessages via the communication link. The LED drivers 234A, 234B, 234Cmay be coupled to a power source, such as an alternating-current (AC)power source and/or a direct-current (DC) power source, and may beconfigured to control the amount of power delivered to the respectiveLED light sources 232A, 232B, 232C to adjust the intensity of the LEDlight sources. The LED drivers 234A, 234B, 234C may be configured toindividually control the LED light sources 232A, 232B, 232C in responseto the digital messages received via the communication link 204. Forexample, the lighting fixture 230 may be acontrollable-color-temperature lighting fixture (e.g., an RGB lightingfixture), where the LED light source 232A is a red LED light source, theLED light source 232B is a green LED light source, and the LED lightsource 232C is a blue LED light source. The LED drivers 234A, 234B, 234Cmay be configured to adjust the intensities of the light emitted by therespective LED light sources 232A, 232B, 232C to control the color(e.g., the color temperature) of the cumulative light emitted by thelighting fixture 230, for example, in response to a single commandreceived via the communication link 204. The single command may includean identification (e.g., address) of the lighting fixture 220 to becontrolled.

The single command may include a desired color (e.g., a desired colortemperature) value of the composite light being emitted from thelighting fixture 230, and/or the single command may include the desiredoverall or combined intensity level of the of the lighting fixture 230.For example, the LED drivers 234A, 234B, 234C may be configured tocontrol the respective LED light sources 232A, 232B, 232C to emit adesired color (e.g., a desired color temperature) and/or combinedintensity, based on the single command. The color temperature valueincluded in the single command may be a color temperature value alongthe black body temperature curve depicted in FIG. 1. The single commandmay include the desired intensity levels of discrete-spectrum lightsources, e.g., the single command may include the desired intensitylevels of the LED light source 232A, the LED light source 232B, and theLED light source 232C. For example, the LED drivers 234A, 234B, 234C maybe configured to control the color, color temperature, and/or intensitylevel of the lighting fixture 230, based on the single command.

The single command may include a desired color trajectory value of thecomposite light to be emitted from the controlled lighting fixture 230.The desired color trajectory may be a desired color temperature for thelighting fixture 230 with respect to a desired total intensity for thecumulative light emitted by the lighting fixture 230 (e.g., when theintensity of the lighting fixture 230 is being adjusted as describedherein). For example, the single command may include the desired totalintensity for the lighting fixture 230 and the LED drivers 234A, 234B,234C may be configured to control the respective LED light sources 232A,232B, 232C to cause the lighting fixture 230 to emit a color temperatureas defined by the desired color trajectory. The color trajectory maycorrespond to the color temperature of a specific lamp (e.g., anincandescent lamp, a halogen lamp, or a fluorescent lamp), as the lampis dimmed. For example, the color trajectory of the LED light fixture230 may mimic an incandescent lamp when dimmed from a low-end intensityto a high-end intensity.

The single command may include a desired color map value of thecomposite light to be emitted from the lighting fixture 230. Forexample, the single command may include the x and y coordinates of aspecific color on the color map depicted in FIG. 1, and may also includea z parameter corresponding to a desired intensity of the specificcolor.

The single command may include hue and/or saturation parameters of aspecific color to be emitted from the lighting fixture 230, and may alsoinclude a z parameter corresponding to a desired intensity of thespecific color. The single command may include red, green, and blue(RGB) parameters of a specific color to be emitted from the lightingfixture 230, and may also include a z parameter corresponding to adesired intensity of the specific color.

The LED drivers 234A, 234B, 234C of the lighting fixture 230 may beassigned a unique light engine (e.g., a color engine) that defines theappropriate intensities to which to control the respective LED lightsource in response to commands received via the communication link 204.The LED drivers 234A, 234B, 234C may use the color engines during normaloperation of the load control system 200 to determine the appropriateintensity to control the respective LED light source to achieve adesired color, color temperature, color trajectory, color mapping, hue,saturation, and/or RGB colors for lighting fixture 230. For example, thecolor engine may define a fixed color (e.g., a fixed color temperature)for the lighting fixture 230.

The load control system 200 may further comprise a system controller 240(e.g., a central controller or a load controller) coupled to the digitalcommunication link 204 for transmitting and receiving digital messages.For example, the system controller 240 may be configured to transmitdigital messages to the LED drivers of the lighting fixtures 210, 220,230 for turning the lighting fixtures on and off and/or adjusting atleast one of the intensity, color, and/or the color temperature of thecumulative light emitted by the respective lighting fixture. Forexample, the system controller 240 may be configured to transmit asingle command to both of the LED drivers 224A, 224B of the lightingfixture 220 to cause both of the LED drivers to appropriately controlthe respective LED light sources 222A, 222B to control the color (e.g.,the color temperature) of the cumulative light emitted by the lightingfixture 220 to a desired color (e.g., a desired color temperature).Similarly, the system controller 240 may be configured to transmit asingle command to the LED drivers 234A, 234B, 234C of the lightingfixture 230 to cause the LED drivers to appropriately control therespective LED light sources 232A, 232B, 232C to control the color(e.g., the color temperature) of the cumulative light emitted by thelighting fixture 230 to a desired color (e.g., a desired colortemperature).

The digital communication link 204 may comprise a wired communicationlink, for example, a digital communication link operating in accordancewith a predefined communication protocol (such as, for example, one ofEthernet, IP, XML, Web Services, QS, DMX, BACnet, Modbus, LonWorks,and/or KNX protocols), a serial digital communication link, an RS-485communication link, an RS-232 communication link, a digital addressablelighting interface (DALI) communication link, and/or a LUTRON ECOSYSTEMcommunication link. The digital communication link 204 may comprise awireless communication link, for example, a radio-frequency (RF),infrared (IR), and/or optical communication link. Digital messages maybe transmitted on an RF communication link using, for example, one ormore of a plurality protocols, such as the LUTRON CLEARCONNECT, WIFI,ZIGBEE, Z-WAVE, KNX-RF, and/or ENOCEAN RADIO protocols.

The load control system 200 may comprise one or more input devices,e.g., such as a remote control device 250, an occupancy sensor 252,and/or a daylight sensor 254. The remote control device 250, theoccupancy sensor 252, and/or the daylight sensor 254 may bebattery-powered wireless control devices (e.g., RF transmitters)configured to transmit digital messages to the system controller 240 viawireless signals, e.g., RF signals 206 (e.g., directly to the systemcontroller 240). The load control system 200 may comprise a wirelessadapter device 256 coupled to the digital communication link 204 andconfigured to receive the RF signals 206. The wireless adapter device256 may be configured to transmit one or more digital messages to thesystem controller 240 via the digital communication link 204 in responseto digital messages received from one of the wireless control devicesvia the RF signals 206. For example, the wireless adapter device 256 mayre-transmit the digital messages received from the wireless controldevices on the digital communication link 204. The system controller 240may be configured to transmit one or more digital messages to the LEDdrivers in response to the digital messages received from the remotecontrol device 250, the occupancy sensor 252, and/or the daylight sensor254. An example of a load control system for controlling the colortemperatures of lighting fixtures in response to different types ofinput devices is described in greater detail in commonly-assigned U.S.Patent Application Publication No. 2014/0312777, published Oct. 23,2014, entitled SYSTEMS AND METHODS FOR CONTROLLING COLOR TEMPERATURE,the entire disclosure of which is hereby incorporated by reference

The remote control device 250 may provide for manual control of theintensities, colors, and/or color temperatures of the lighting fixtures210, 220, 230. The remote control device 250 may comprise one or morebuttons for receiving user inputs. For example, buttons corresponding toscenes may be provided on the remote control device 250. As an example,buttons corresponding to different lighting presets or scenes (e.g., anentertaining scene, a cooking scene, a bedtime scene, a movie scene, andthe like) may be provided on the remote control device 250. For example,the lighting fixtures 210, 220, 230 may be controlled to emit differentcolor temperatures depending on the selected preset or scene. The remotecontrol device 250 may be configured to transmit digital messages to thesystem controller 240 via the RF signals 206 in response to an actuationof one or more of the buttons and/or scenes.

The occupancy sensor 252 may be configured to detect occupancy and/orvacancy conditions in the space in which the load control system 200 isinstalled. The occupancy sensor 252 may transmit digital messages to thesystem controller 240 via the RF signals 206 in response to detectingthe occupancy and/or vacancy conditions. The system controller 240 mayeach be configured to turn one or more of the LED light sources of thelighting fixtures 210, 220, 230 on and off in response to receiving anoccupied command and a vacant command, respectively. For example, thelighting fixtures 210, 220, 230 may be controlled to emit colortemperatures that correspond to more efficient operation of therespective LED drivers in response to detecting a vacancy condition inthe space. The occupancy sensor 252 may operate as a vacancy sensor,such that the LED light sources are turned off in response to detectinga vacancy condition (e.g., not turned on in response to detecting anoccupancy condition). Examples of RF load control systems havingoccupancy and vacancy sensors are described in greater detail incommonly-assigned U.S. Pat. No. 8,009,042, issued Aug. 30, 2011,entitled RADIO-FREQUENCY LIGHTING CONTROL SYSTEM WITH OCCUPANCY SENSING;U.S. Pat. No. 8,199,010, issued Jun. 12, 2012, entitled METHOD ANDAPPARATUS FOR CONFIGURING A WIRELESS SENSOR; and U.S. Pat. No.8,228,184, issued Jul. 24, 2012, entitled BATTERY-POWERED OCCUPANCYSENSOR, the entire disclosures of which are hereby incorporated byreference.

The daylight sensor 254 may be configured to measure a total lightintensity in the space in which the load control system is installed.The daylight sensor 254 may transmit digital messages including themeasured light intensity to the system controller 240 via the RF signals206 for controlling the intensities, colors, and/or the colortemperatures of one or more of the LED light sources of the lightingfixtures 210, 220, 230 in response to the measured light intensity.Examples of RF load control systems having daylight sensors aredescribed in greater detail in commonly-assigned U.S. Pat. No.8,410,706, issued Apr. 2, 2013, entitled METHOD OF CALIBRATING ADAYLIGHT SENSOR; and U.S. Pat. No. 8,451,116, issued May 28, 2013,entitled WIRELESS BATTERY-POWERED DAYLIGHT SENSOR, the entiredisclosures of which are hereby incorporated by reference.

The load control system 200 may comprise other types of input devices,such as, for example, temperature sensors; humidity sensors;radiometers; window sensors; shadow sensors; cloudy-day sensors;pressure sensors; smoke detectors; carbon monoxide detectors;air-quality sensors; motion sensors; security sensors; proximitysensors; fixture sensors; partition sensors; keypads; kinetic orsolar-powered remote controls; key fobs; cell phones; smart phones;tablets; personal digital assistants; personal computers; laptops;timeclocks; audio-visual controls; safety devices; power monitoringdevices (such as power meters, energy meters, utility submeters, utilityrate meters, etc.), central control transmitters; residential,commercial, or industrial controllers, or any combination of these inputdevices. Examples of load control systems are described in greaterdetail in commonly-assigned U.S. Patent Application Publication No.2014/0001977, published Jan. 2, 2014, entitled LOAD CONTROL SYSTEMHAVING INDEPENDENTLY-CONTROLLED UNITS RESPONSIVE TO A BROADCASTCONTROLLER, and U.S. Patent Application Publication No. 2014/0265568,published Sep. 18, 2014, entitled COMMISSIONING LOAD CONTROL SYSTEMS,the entire disclosures of which are hereby incorporated by reference.

The LED drivers of each of the lighting fixtures 220, 230 may beconfigured during a configuration procedure that may be executed priorto shipment of the LED drivers to the installation site of the loadcontrol system 200. For example, the LED drivers of each of the lightingfixtures 220, 230 may be configured using a configuration tool at anoriginal equipment manufacturer (OEM). During the configurationprocedure, the LED drivers of each of the lighting fixtures 220, 230(e.g., the LED drivers of the respective lighting fixtures 220, 230) maybe assigned an identical fixture address, e.g., a fixture serial number(e.g., the same fixture address or serial number to each of the LEDdrivers). For example, the LED drivers of the lighting fixture 220 mayeach be assigned a first fixture address and the LED drivers of thelighting fixture 230 may each be assigned a second fixture address. TheLED drivers of each of the lighting fixtures 220, 230 may be assigned aunique sub-address that uniquely identifies the LED driver within therespective lighting fixture during the configuration procedure. Forexample, the LED drivers 224A, 224B of the lighting fixture 220 may beassigned sub-addresses of one and two, respectively. The LED drivers234A, 234B, 234C of the lighting fixture 230 may be assignedsub-addresses of one, two, and three, respectively. An example of aconfiguration tool for an LED driver is described in greater detail incommonly-assigned U.S. Pat. No. 8,810,159, issued Aug. 19, 2014,entitled SYSTEM AND METHOD FOR PROGRAMMING A CONFIGURABLE LOAD CONTROLDEVICE, the entire disclosure of which is hereby incorporated byreference.

The LED drivers of each of the lighting fixtures 220, 230 may beassigned a unique light engine (e.g., a color engine) that defines theappropriate intensities to which to control the respective LED lightsource in response to commands received via the communication link 204.The LED drivers may use the color engine during normal operation of theload control system 200 to determine the appropriate intensity to whichto control the respective LED light source to achieve a desired color(e.g., a desired color temperature) for the respective lighting fixture.For example, the color engine may define a fixed color (e.g., a fixedcolor temperature) for the lighting fixture. The color engine may definea color trajectory, which may be a desired color temperature for thelighting fixture with respect to a desired total intensity for thecumulative light emitted by the lighting fixture (e.g., when theintensity of the lighting fixture 220 is being adjusted as describedabove). The color trajectory may correspond to the color temperature ofa specific lamp (e.g., an incandescent lamp, a halogen lamp, or afluorescent lamp) as the lamp is dimmed. For example, the colortrajectory of an LED light fixture may mimic an incandescent lamp whendimmed from a low-end intensity to a high-end intensity. Further, thecolor engine may define a color map for the lighting fixture, where asingle command transmitted to the LED drivers of a lighting fixture mayidentify a specific color (e.g., a specific color temperature) for thelighting fixture (e.g., controlling the color (e.g., the colortemperature) of the lighting fixture 230 to any color temperature asdescribed herein).

After the configuration procedure, the LED light sources and the LEDdrivers may be installed in the lighting fixtures 220, 230 prior toshipment to the installation site of the load control system 200, forexample, at the OEM. The lighting fixtures 220, 230 may be calibratedduring a calibration procedure prior to shipment to the installationsite of the load control system 200. For example, the color (e.g., thecolor temperature) of the cumulative light emitted by each of thelighting fixtures 220, 230 may be measured at various operating pointsand the color engines in the LED drivers may be adjusted to ensure thatthe cumulative light emitted by the lighting fixtures has the correctcolor (e.g., the correct color temperature) at the various operatingpoints.

After the lighting fixtures 220, 230 are shipped and installed at theinstallation site, the load control system 200 may be programmed duringa setup and commissioning procedure. During the setup and commissioningprocedure, the system controller 240 may assign a link address to eachof the LED drivers on the communication link 204. The link address maybe included in the digital messages transmitted to each of the LEDdrivers during normal operation of the load control system 200 forperforming load control. For example, the system controller 240 mayassign a first link address to the LED driver 214 of the lightingfixture 210. For the lighting fixtures 220, 230 that have multiple LEDdrivers, the system controller 240 may use the fixture address of theLED drivers to assign the same link address to the LED drivers of asingle fixture. For example, the system controller 240 may assign asecond link address to the LED drivers 224A, 224B of the lightingfixture 220 since these LED drivers have the same fixture address (whichmay be assigned during the configuration procedure of the LED drivers).The system controller 240 may assign a third link address to the LEDdrivers 234A, 234B, 234C of the lighting fixture 230.

The system controller 240 may be configured to transmit a single digitalmessage to each of the LED drivers 224A, 224B in the lighting fixture220 by including the link address of the lighting fixture 220 in thedigital message. The single digital message transmitted to each of theLED drivers 224A, 224B may be used to control each respective LED lightsource 222A, 222B, e.g., to control the intensity levels of the LEDlight source 222A and the LED light source 222B. The single digitalmessage may also include a command to control the cumulative lightemitted by the lighting fixture 220 to a specific color (e.g., aspecific color temperature). The LED drivers 224A, 224B may each receivethe digital message and may use the stored color engine to determine howto control the respective LED light source 222A, 222B to achieve thecorrect color (e.g., the correct color temperature) for the lightingfixture 220. Similarly, the system controller 240 may be configured totransmit a single digital message to the LED drivers 234A, 234B, 234C inthe lighting fixture 230 by including the link address of the lightingfixture 230 in the digital message.

The system controller 240 may be configured to transmit a digitalmessage directly to one or more of the LED drivers 224A, 224B using thelink address of the lighting fixture 220 and the sub-address of therespective LED driver (e.g., as was stored in the LED driver during theconfiguration procedure). For example, the system controller 240 may beconfigured to transmit a digital message to the LED driver 224B of thelighting fixture 220 using the first link address and the sub-addresstwo. The LED drivers of the lighting fixtures 220, 230 may include thelink address of the lighting fixture and the sub-address of therespective LED driver in any digital messages transmitted on thecommunication link 204 to specify which LED driver transmitted thedigital message. Similarly, the system controller 240 may be configuredto transmit a digital message directly to one of the LED drivers 234A,234B, 234C using the link address of the lighting fixture 230 and thesub-address of the respective LED driver.

The LED drivers of the multi-channel lighting fixtures (e.g., thelighting fixtures 220, 230) may operate to provide a wider output rangeat a single color (e.g., a single color temperature) (e.g., rather thanoperating to adjust the color (e.g., the color temperature) of thecumulative light emitted by the respective lighting fixture). Forexample, the LED light sources 222A, 222B of the lighting fixture 220may be characterized by the same color (e.g., the same colortemperature), and the LED drivers 224A, 224B may have different powerratings to provide a wider output range for the lighting fixture 220than if the LED drivers had the same power ratings. The LED driver 224Afor the LED light source 222A may have, for example, a higher powerrating than the LED driver 224B for the LED light source 222B. The LEDdriver 224A may adjust the intensity of the LED light source 222A toadjust the total intensity of the cumulative light emitted by thelighting fixture 220 from approximately 100% to 10%, and the LED driver224B may adjust the intensity of the LED light source 222B to adjust thetotal intensity of the cumulative light emitted by the lighting fixture220 from approximately 10% to 1%. Though example power ratings areprovided herein, other power ratings may be used for different LEDdrivers to control the total light emitted by a lighting fixture.

The load control system 200 may comprise one or more other types of loadcontrol devices, such as, for example, a dimming circuit for a lightingload, such as incandescent lamp or halogen lamp; an electronic dimmingballast for a fluorescent lamp; a screw-in luminaire including a dimmercircuit and an incandescent or halogen lamp; a screw-in luminaireincluding a ballast and a compact fluorescent lamp; and a screw-inluminaire including an LED driver and an LED light source.

FIG. 3 is a simple diagram of another example load control system 300having a plurality of lighting fixtures 310, 320, 330 for illuminating aspace. The lighting fixture 310 may comprise a single lighting load(e.g., an LED light source 312) and a load regulation device (e.g., anLED driver 314) for controlling the LED light source. The LED driver 314may be configured to control the LED light source 312 in response todigital messages received via a digital communication link 304. The LEDdriver 314 may be configured to transmit a digital message includingfeedback information via the digital communication link 304. The digitalcommunication link 304 may be similar to the digital communication link204 of the load control system 200 shown in FIG. 2.

The lighting fixture 320 may comprise multiple lighting loads (e.g., LEDlight sources 322A, 322B) and respective load regulation devices (e.g.,LED drivers 324A, 324B). The lighting fixture 320 may comprise a controlmodule 326 coupled to the digital communication link 304. The controlmodule 326 may be coupled to the LED drivers 324A, 324B via a fixturecontrol link 328, which may comprise a digital communication link (e.g.,a wired or wireless communication link). Alternatively, or additionally,the fixture control link 328 could comprise an analog control link. Thecontrol module 326 may be configured to individually control the LEDdrivers 324A, 324B in response to digital messages received via thecommunication link 304.

The control module 326 and/or the LED drivers 324A, 324B of the lightingfixture 320 may be assigned a unique light engine (e.g., a color engine)that defines the appropriate intensities to which to control therespective LED light source in response to commands received via thecommunication link 304. The control module 326 may send instructions toLED drivers 324A, 324B, for controlling the respective LED lightsource(s) to achieve a desired color, color temperature, colortrajectory, color mapping, hue, saturation, and/or RGB colors forlighting fixture 320. In an example, the control module 326 may sendinstructions to the address (e.g., sub-addresses) of LED drivers 324A,324B, for controlling the intensities of each of the respective LEDlight sources. This may allow legacy LED drivers to be used in certainimplementations.

The LED drivers 324A, 324B may use color engines during normal operationof the load control system 300 to, for example, determine theappropriate intensity to control the respective LED light source(s) toachieve a desired color, color temperature, color trajectory, colormapping, hue, saturation, and/or RGB colors for lighting fixture 320.For example, the color engines may define a fixed color (e.g., a fixedcolor temperature) for the lighting fixture 320.

As in the load control system of FIG. 2, the lighting fixture 320 maybe, for example, a controllable-color-temperature lighting fixture wherethe LED light sources 322A, 322B are different color LED light sources(e.g., white and red LED light sources, respectively). The controlmodule 326 may be configured to individually control the LED drivers324A, 324B to adjust the intensities of the white light emitted by theLED light source 322A and the red light emitted by the LED light source322B, respectively, to control the color (e.g., the color temperature)of the cumulative light emitted by the lighting fixture 320, forexample, in response to a single command received via the communicationlink 304.

The single command may include parameters as described herein. Forexample, the single command may include a desired color, colortemperature, color trajectory, color mapping, hue, saturation, and/orRGB value of the composite light being emitted from the lighting fixture320, as described herein. The single command may include the desiredoverall or combined intensity level of the lighting fixture 320. Forexample, the LED drivers 324A, 324B may be configured to control therespective LED light sources 322A, 322B to emit a desired color (e.g., adesired color temperature) and/or combined intensity, based on thesingle command. The single command may include the desired intensitylevels of discrete-spectrum light sources, e.g., the single command mayinclude parameters that identify the desired intensity levels of the LEDlight source 322A and the LED light source 322B. For example, thecontrol module 326 may be configured to control the cumulative lightemitted by the lighting fixture 320 to become redder as the totalintensity of the cumulative light is decreased (e.g., dimmed). The LEDdrivers 324A, 324B may be configured to transmit feedback to the controlmodule 326 via the fixture control link 328.

The lighting fixture 330 may comprise a plurality of lighting loads(e.g., LED light sources 332A, 332B, 332C) and respective loadregulation devices (e.g., LED drivers 334A, 334B, 334C). The lightingfixture 330 may also comprise a control module 336 coupled to thedigital communication link 304. The control module 336 may be coupled tothe LED drivers 334A, 334B, 334C via a fixture control link 338, whichmay comprise a digital communication link or an analog control link. Thecontrol module 336 may be configured to individually control the LEDdrivers 334A, 334B, 334C in response to the digital messages receivedvia the communication link 304.

The control module 336 and/or the LED drivers 334A, 334B, 334C of thelighting fixture 330 may be assigned a unique light engine (e.g., acolor engine) that defines the appropriate intensities to which tocontrol the respective LED light source in response to commands receivedvia the communication link 304. The control module 336 may sendinstructions to LED drivers 334A, 334B, 334C, for controlling therespective LED light source(s) to achieve a desired color, colortemperature, color trajectory, color mapping, hue, saturation, and/orRGB colors for lighting fixture 330. In an example, the control module336 may send instructions to the address (e.g., sub-addresses) of LEDdrivers 334A, 334B, 334C, for controlling the intensities of each of therespective LED light sources. This may allow legacy LED drivers to beused in certain implementations.

The LED drivers 334A, 334B, 334C may use color engines during normaloperation of the load control system 300 to, for example, determine theappropriate intensity to control the respective LED light source(s) toachieve a desired color, color temperature, color trajectory, colormapping, hue, saturation, and/or RGB colors for lighting fixture 330.For example, the color engine may define a fixed color (e.g., a fixedcolor temperature) for the lighting fixture 330.

The lighting fixture 330 may be a controllable-color-temperaturelighting fixture (e.g., an RGB lighting fixture), where the LED lightsources 332A, 332B, 332C are different color LED light sources (e.g.,red, green, and blue LED light sources, respectively). The controlmodule 336 may be configured to control the LED drivers 334A, 334B, 334Cto adjust the intensities of the light emitted by the respective LEDlight sources 332A, 332B, 332C to control the color (e.g., the colortemperature) of the cumulative light emitted by the lighting fixture330, for example, in response to a single command received via thecommunication link 304, as described herein.

The single command may include a desired color (e.g., a desired colortemperature) value of the composite light being emitted from thelighting fixture 330, and/or the single command may include the desiredoverall or combined intensity level of the of the lighting fixture 330.For example, the LED drivers 334A, 334B, 334C may be configured tocontrol the respective LED light sources 332A, 332B, 332C to emit adesired color (e.g., a desired color temperature) and/or combinedintensity, based on the single command. The single command may includethe desired intensity levels of discrete-spectrum light sources, e.g.,the single command may include the desired intensity levels of the LEDlight source 332A, the LED light source 332B, and the LED light source332C. For example, the control module 336 may be configured to controlthe color (e.g., the color temperature) of the cumulative light emittedby the lighting fixture 330 to any desired color (e.g., any desiredcolor temperature). The LED drivers 334A, 334B, 334C may be configuredto transmit feedback to the control module 336 via the fixture controllink 338.

The load control system 300 may further comprise a system controller 340coupled to the digital communication link 304 for transmitting andreceiving digital messages. For example, the system controller 340 maybe configured to transmit digital messages directly to the LED driver314 for controlling the LED light source 312 of the lighting fixture310. The system controller 340 may be configured to transmit digitalmessages to the control modules 326, 336 of the lighting fixtures 320,330 for turning the lighting fixtures on and off and/or adjusting atleast one of the intensity, color, and color temperature of thecumulative light emitted by the respective lighting fixture. The controlmodules 326, 336 may be configured to transmit digital messages (e.g.,including the feedback received from the respective LED drivers) to thesystem controller 340. Feedback may include present current and/orvoltage levels of the respective LED drivers, faulting and/or missingcolor engines of the respective LED drivers, hours of operation of therespective LED drivers, thermal states of the respective LED drivers,internally computed power levels of the respective LED drivers, and thelike.

The load control system 300 may comprise one or more input devices,e.g., such as a remote control device 350, an occupancy sensor 352,and/or a daylight sensor 354, which may operate in a similar manner asthe remote control device 250, the occupancy sensor 252, and thedaylight sensor 254, respectively, of the load control system 200 shownin FIG. 2. The input devices may be configured to transmit digitalmessages directly to the system controller 340 via RF signals 306. Theload control system 300 may comprise a wireless adapter device 356configured to transmit digital messages to the system controller 340 viathe communication link 304 in response to digital message received fromthe input devices via the RF signals 306.

During a setup and commissioning procedure of the load control system300, the system controller 340 may be configured to assign a linkaddress to each of the LED driver 314 of the lighting fixture 310 andthe control modules 326, 336 of the lighting fixtures 320, 330 for usein communication during normal lighting control operation of the loadcontrol system 300. For example, the system controller 340 may assign afirst link address to the LED driver 314 of the lighting fixture 310, asecond link address to the control module 326 of the lighting fixture320, and a third link address to the control module 336 of the lightingfixture 330.

The LED drivers of each of the lighting fixtures 320, 330 may each beassigned a unique fixture-control-link address that uniquely identifiesthe LED driver within the respective lighting fixture. For example, theunique fixture-control-link addresses may be assigned to the LED driversduring a configuration procedure at an OEM or by the control modules326, 336 after installation. The control modules 326, 336 may use theunique fixture-control-link addresses to individually control therespective LED drivers. The unique fixture-control-link addresses may becommunicated to the control modules 326, 336 or pre-stored at thecontrol modules 326, 336 and determined to control each of the localdrivers. The control modules 326, 336 may be assigned a color engine forappropriately controlling the LED light sources in the respectivelighting fixture 320, 330 to the correct color (e.g., colortemperature), for example, during the configuration procedure at theOEM. The color engine may define a fixed color, color temperature, colortrajectory, color map, hue, saturation, and/or RGB value.

FIG. 4 is a simple diagram of another example load control system 400having a plurality of lighting fixtures 410, 420, 430 for illuminating aspace. The load control system 400 of FIG. 4 may operate in a similarmanner as the load control system 300 of FIG. 3. The lighting fixtures420, 430 of the load control system 400 may comprise master LED drivers424A, 434A. The master LED driver 424A, 434A may be coupled to a digitalcommunication link 404 for transmitting and receiving digital messages.

For example, the master LED driver 424A of the lighting fixture 420 maybe directly coupled to an LED light source 422A (e.g., a white LED lightsource) and may be configured to control the amount of power deliveredfrom a power source to the LED light source 422A to adjust the intensityof the LED light source. The master LED driver 424A may be coupled via afixture control link 428 to a slave LED driver 424B, which may becoupled to an LED light source 422B (e.g., a red LED light source). Themaster LED driver 424A may be configured to control the slave LED driver424B via the fixture control link 428. The master LED driver 424A may beconfigured to directly adjust the intensity of the white LED lightsource 422A and to control the slave LED driver 424B to adjust theintensity of the red LED light source 422B in response to a digitalmessage received via the communication link 404.

The master LED driver 424A may be configured to control the intensitiesof the LED light sources 422A, 422B to control the intensity, color,and/or color temperature of the cumulative light emitted by the lightingfixture 420 (e.g., in a similar manner as the control module 326 of theload control system 300 shown in FIG. 3). The master LED driver 424A maybe configured to control the intensities of the LED light sources 422A,422B to control the intensity, color, and/or color temperature of thecumulative light emitted by the lighting fixture 420, for example, inresponse to a single command received via the communication link 404.

The single command may include parameters as described herein. Forexample, the single command may include a desired color, colortemperature, color trajectory, color mapping, hue, saturation, and/orRGB value of the composite light being emitted from the lighting fixture420, as described herein, and/or the single command may include thedesired overall or combined intensity level of the of the lightingfixture 420. The single command may include the desired intensity levelsof discrete-spectrum light sources, e.g., the single command may includethe desired intensity levels of the LED light source 422A and the LEDlight source 422B. For example, the master LED driver 424A may beconfigured to control the cumulative light emitted by the lightingfixture 420 to become redder as the total intensity of the cumulativelight is decreased (e.g., dimmed). The slave LED driver 424B may beconfigured to transmit feedback to the master LED driver 424A via thefixture control link 428. The master driver 424A may receive a totaldesired intensity level, color, and/or color temperature, and controlthe LED light source 422A and the slave driver 424B to output thedesired intensity level, color, and/or color temperature.

The master LED driver 434A of the lighting fixture 430 may be directlycoupled to an LED light source 432A (e.g., a red LED light source) andmay be configured to control the amount of power delivered from thepower source to the LED light source 432A to adjust the intensity of theLED light source. The master LED driver 434A may be coupled to slave LEDdrivers 434B, 434C via a fixture control link 438. The slave LED drivers434B, 434C of the lighting fixture 430 may be coupled to LED lightsource 432B, 432C, e.g., a green LED light source and a blue LED lightsource, respectively. The master LED driver 434A of the lighting fixture430 may be configured to directly adjust the intensity of the red LEDlight source 432A and to control the slave LED drivers 434B, 434C toadjust the intensities of the green LED light source 432B and the blueLED light source 432C, respectively, in response to a digital messagereceived via the communication link 404. The master LED driver 424A maybe configured to control the intensities of the LED light sources 432A,432B, 432C to control the intensity, color, and/or the color temperatureof the cumulative light emitted by the lighting fixture 430 (e.g., in asimilar manner as the control module 336 of the load control system 300shown in FIG. 3). The master LED driver 434A may be configured tocontrol the intensities of the LED light sources 432A, 432B, 432C tocontrol the intensity, color, and/or color temperature of the cumulativelight emitted by the lighting fixture 430, for example, in response to asingle command received via the communication link 404.

The single command may include a desired color (e.g., a desired colortemperature) value of the composite light being emitted from thelighting fixture 430, and/or the single command may include the desiredoverall or combined intensity level of the of the lighting fixture 430.The single command may include the desired intensity levels ofdiscrete-spectrum light sources, e.g., the single command may includethe desired intensity levels of the LED light source 432A, the LED lightsource 432B, and the LED light source 432C. For example, the master LEDdriver 434A may be configured to control the color (e.g., the colortemperature) of the cumulative light emitted by the lighting fixture 430to any desired color (e.g., any desired color temperature). The slaveLED drivers 434B, 434C may be configured to transmit feedback to themaster LED driver 434A via the fixture control link 438.

The load control system 400 may further comprise a system controller 440coupled to the digital communication link 404 for transmitting andreceiving digital messages. The system controller 440 may be configuredto transmit digital messages to the driver 414 of the lighting fixture410 and/or the master LED drivers 424A, 434A of the lighting fixtures420, 430 for turning the lighting fixtures on and off and/or adjustingat least one of the intensity, color, and color temperature of thecumulative light emitted by the respective lighting fixture. The masterLED drivers 424A, 434A may be configured to transmit digital messages(e.g., including the feedback from the master LED drivers and feedbackreceived from the slave LED drivers) to the system controller 440.

The load control system 400 may comprise one or more input devices,e.g., such as a remote control device 450, an occupancy sensor 452,and/or a daylight sensor 454, which may operate in a similar manner asrespective input devices of the load control systems 200, 300 shown inFIGS. 2 and 3. The input devices may be configured to transmit digitalmessages directly to the system controller 440 via RF signals 406. Theload control system 400 may also comprise a wireless adapter device 456configured to transmit digital messages to the system controller 440 viathe communication link 404 in response to a digital message receivedfrom the input devices via the RF signals 406.

During a setup and commissioning procedure of the load control system400, the system controller 440 may be configured to assign a unique linkaddress to the LED driver 414 of the lighting fixture 410 and the masterLED drivers 424A, 434A of the lighting fixtures 420, 430 for use incommunication during normal lighting control operation of the loadcontrol system 400. For example, the system controller 440 may assign afirst link address to the LED driver 414 of the lighting fixture 410, asecond link address to the master LED driver 424A of the lightingfixture 420, and a third link address to the master LED driver 434A ofthe lighting fixture 430.

The slave LED drivers of each of the lighting fixtures 420, 430 may eachbe assigned a unique slave address that uniquely identifies the slaveLED drivers within the respective lighting fixture. For example, theunique slave addresses may be assigned to the LED drivers during aconfiguration procedure at an OEM or by the master LED drivers 424A,434A after installation. The master LED drivers 424A, 434A may use theunique slave addresses to individually control the respective slave LEDdrivers.

The master LED drivers 424A, 434A may be assigned a color engine forappropriately controlling the LED light sources in the respectivelighting fixture 420, 430 to the correct color (e.g., the correct colortemperature), for example, during the configuration procedure at theOEM. The color engine may define a fixed color, color temperature, colortrajectory, color map, hue, saturation, and/or RGB value. The master LEDdrivers 424A, 434A may send instructions to respective slave LED drivers434B, 434C, for controlling the respective LED light source(s) toachieve a desired color, color temperature, color trajectory, colormapping, hue, saturation, and/or RGB colors for lighting fixtures 420,430. In an example, the master LED drivers 424A, 434A may sendinstructions to the address(es) (e.g., sub-addresses) of respectiveslave LED drivers 434B, 434C, for controlling the intensities of each ofthe respective LED light sources. This may allow legacy LED drivers tobe used in certain implementations.

Each of the master LED drivers 424A, 434A may be assigned a color enginefor controlling the LED light source directly coupled to the master LEDdriver, and each of the slave LED drivers may be assigned a respectivecolor engine for controlling LED light source directly coupled to theslave LED driver. Though FIG. 4 shows a master driver 424A, 434Adirectly controlling a single LED, the master drivers 424A, 434A maydirectly control multiple LEDs. Though FIG. 4 shows the master drivers424A, 434A directly controlling LEDs of a certain color, the masterdrivers 424A, 434A may directly control LEDs of other colors.

In contrast to multi-channel LED drivers for controlling multi-channellighting fixtures, the load control systems 200, 300, 400 of FIGS. 2-4may each provide a modular solution for providing multi-channel lightingfixtures since each of the multi-channel lighting fixtures each includemultiple LED drivers for controlling the respective LED light sources.The multi-channel lighting fixtures may each comprise more than threeLED drivers for controlling more than three LED light sources, forexample, as many LED drivers as desired to produce the desired color(e.g., the desired color temperature) of the cumulative light and/oroutput power range. Each of the LED drivers may be sized correctly(e.g., with the correct power rating) depending upon the LED lightsource to be controlled and the desired contribution of that LED lightsource on the cumulative light emitted by the lighting fixture. If oneof the LED drivers of a multi-channel lighting fixture happens to fail,the light fixture may still emit light since the other LED drivers maystill be operating correctly.

FIG. 5A is a simplified block diagram of an example load regulationdevice, e.g., an LED driver 500, which may be deployed as one of the LEDdrivers in the load control systems 200, 300 shown in FIGS. 2 & 3. TheLED driver 500 of FIG. 5A may be deployed as one of the slave LEDdrivers in the load control system 400 of FIG. 4. The LED driver 500 maybe arranged to control the amount of power delivered to an electricalload, such as, an LED light source 502, and thus the intensity of theLED light source. The LED driver 500 may comprise a hot terminal H and aneutral terminal N that are adapted to be coupled to a power source,e.g., an AC power source.

The LED driver 500 may comprise a load regulation circuit 510, which maycontrol the amount of power delivered to the LED light source 502 so asto control the intensity of the LED light source between a low-end(e.g., minimum) intensity L_(LE) (e.g., approximately 1-5%) and ahigh-end (e.g., maximum) intensity L_(LE) (e.g., approximately 100%).The load regulation circuit 510 may comprise, for example, a forwardconverter, a boost converter, a buck converter, a flyback converter, alinear regulator, or any suitable LED drive circuit for adjusting theintensity of the LED light source 502. Examples of load regulationcircuits for LED drivers are described in greater detail incommonly-assigned U.S. Pat. No. 8,492,987, issued Jul. 23, 2010, andU.S. Patent Application Publication No. 2014/0009085, published Jan. 9,2014, both entitled LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHTSOURCE, the entire disclosures of which are hereby incorporated byreference in their entireties.

The LED driver 500 may comprise a control circuit 520, e.g., acontroller, for controlling the operation of the load regulation circuit510. The control circuit 520 may comprise, for example, a digitalcontroller or any other suitable processing device, such as, forexample, a microcontroller, a programmable logic device (PLD), amicroprocessor, an application specific integrated circuit (ASIC), or afield-programmable gate array (FPGA).

The control circuit 520 may generate a drive control signal V_(DRIVE)that is provided to the load regulation circuit 510 for adjusting themagnitude of a load voltage V_(LOAD) generated across the LED lightsource 502 and/or the magnitude of a load current I_(LOAD) conductedthrough the LED light source to thus control the intensity of the LEDlight source to a target intensity L_(TRGT). The LED driver 500 mayfurther comprise a voltage sense circuit 522 (which may generate a loadvoltage feedback signal V_(FB-VOLT) that may be indicative of themagnitude of the load voltage V_(LOAD)) and/or a current sense circuit524 (which may generate a load current feedback signal V_(FB-CRNT) thatmay be indicative of the magnitude of the load current I_(LOAD)). Thecontrol circuit 520 may receive the voltage feedback signal V_(FB-VOLT)and the load current feedback signal V_(FB-CRNT), and control the drivecontrol signal V_(DRIVE) to adjust the magnitude of the load voltageV_(LOAD) and/or the magnitude of the load current I_(LOAD) to controlthe intensity of the LED light source 502 to the target intensityL_(TRGT). The control circuit 520 may be configured to control the loadregulation circuit 510 to pulse-width modulate the load voltage V_(LOAD)and/or the load current I_(LOAD) to adjust the intensity of the LEDlight source 502.

The control circuit 520 may be coupled to a memory 526 for storing theoperational characteristics of the LED driver 500 (e.g., the targetintensity L_(TRGT), the low-end intensity L_(LE), the high-end intensityL_(LE), the link address, the slave address, the fixture address and/orserial number, the color engine, etc.). The LED driver 500 may furthercomprise a power supply 528, which generates a direct-current (DC)supply voltage V_(CC) for powering the circuitry of the LED driver.

The LED driver 500 may also comprise a communication circuit 530, whichmay be coupled to a digital communication link, for example, a wiredcommunication link or a wireless communication link, such as aradio-frequency (RF) communication link or an infrared (IR)communication link. The control circuit 520 may be configured to use thecolor engine stored in the memory 526 to update the target intensityL_(TRGT) of the LED light source 502 in dependence upon a commandincluded in a single digital message received via the communicationcircuit 530. The control circuit 520 may be configured to update theoperational characteristics stored in the memory 526 in response todigital messages received via the communication circuit 530. The LEDdriver 500 may be configured to receive a phase-control signal from adimmer switch for determining the target intensity L_(TRGT) for the LEDlight source 502.

FIG. 5B is a simplified block diagram of another example load regulationdevice, e.g., an LED driver 550, which may be deployed as the one of themaster LED drivers 424A, 434A in the load control system 400 shown inFIG. 4. The LED driver 550 may be arranged to control the amount ofpower delivered to an electrical load, such as, an LED light source 552(e.g., one of the LED light sources 422A, 432A), and thus the intensityof the LED light source. The LED driver 550 of FIG. 5B is similar to theLED driver 500 of FIG. 5a . The LED driver 550 comprises a controlcircuit 570 and communication circuits 580, 582. The communicationcircuit 580 may be similar to the communication circuit 430 of the LEDdriver 400 shown in FIG. 4. The communication circuit 580 may be coupledto a digital communication link, for example, a wired communication linkor a wireless communication link, such as a radio-frequency (RF)communication link or an infrared (IR) communication link. The controlcircuit 570 may be configured to transmit and/or receive digitalmessages on the communication link via the communication circuit 580.The communication circuit 582 may allow for control of one or more slaveLED drivers via a fixture control link (e.g., the fixture control links428, 438 shown in FIG. 4). The control circuit 570 may be configured touse the color engine stored in the memory 576 to control the LED lightsource 552 and/or the slave LED drivers coupled to the communicationcircuit 582 in dependence upon a command included in a single digitalmessage received via the communication circuit 580.

FIG. 6 is a simplified block diagram of an example control module 600,which may be deployed as one of the control modules 326, 336 of the loadcontrol system 300 shown in FIG. 3. The control module 600 may beadapted to be coupled in series electrical connection between a powersource (e.g., an AC power source) and one or more load regulationdevices (e.g., the LED drivers of the load control system 300 shown inFIG. 3) for controlling respective lighting loads in a multiple-driverlighting fixture. The control module 600 may comprise an input hotterminal H1 and an input neutral terminal N1 adapted to be electricallycoupled to the AC power source for receiving a line voltage. The controlmodule 600 may comprise an output power connection including an outputhot terminal H2 and an output neutral terminal N2 adapted to be coupledto the load regulation device.

The control module 600 may comprise a controllably conductive device 610coupled in series electrical connection between the input hot terminalH1 and the output hot terminal H2 for controlling the power delivered tothe load regulation device. The controllably conductive device 610 maycomprise, for example, a relay, a bidirectional semiconductor switch(such as, a triac, a FET in a rectifier bridge, two FETs in anti-seriesconnection, or one or more insulated-gate bipolar junction transistors),or any other suitable switching circuit. The controllably conductivedevice 610 may be configured to conduct a load current I_(LOAD) to theload regulation device and the lighting load. The input neutral terminalN1 may be coupled directly to the output neutral terminal N2.

The control module 600 may comprise a control circuit 620 that may becoupled to the controllably conductive device 610 for rendering thecontrollably conductive device conductive and/or non-conductive tocontrol the power delivered to the driver and lighting load. Forexample, the control circuit 620 may comprise a microcontroller, aprogrammable logic device (PLD), a microprocessor, an applicationspecific integrated circuit (ASIC), a field-programmable gate array(FPGA), or any suitable processing device, controller, or controlcircuit. The control circuit 620 may be coupled to a memory 622 forstoring the operational characteristics of the control module 600 (e.g.,the link address, the color engine, etc.). The control module 300 mayfurther comprise a power supply 624 coupled between the input hotterminal H1 and the input neutral terminal N1 for generating adirect-current (DC) supply voltage V_(CC) for powering the controlcircuit 620 and the other low-voltage circuitry of the control module600.

The control module 600 may comprise a current measurement circuit 626coupled in series electrical connection between the input hot terminalH1 and the output hot terminal H2 for measuring the magnitude of theload current I_(LOAD) conducted through the load regulation device andthe lighting load. The current measurement circuit 626 may generate acurrent feedback signal V_(FB-I) indicating the magnitude of loadcurrent I_(LOAD) presently being conducted through the load regulationdevice and the lighting load. For example, the current measurementcircuit 626 may comprise a sense resistor (not shown) for generating asense voltage (e.g., the current feedback signal V_(FB-I)) in responseto the load current I_(LOAD) being conducted through the sense resistor.The control circuit 620 may receive the current measurement signalV_(FB-I) for determining the magnitude of the load current I_(LOAD)being conducted through the load regulation device and the lightingload.

The control module 600 may comprise a voltage measurement circuit 628coupled between the input hot terminal H1 and the input neutral terminalN1 for measuring the magnitude of the line voltage of the AC powersource. The voltage measurement circuit 628 may generate a voltagefeedback signal V_(FB-V) indicating the present magnitude of the linevoltage of the AC power source. For example, the voltage measurementcircuit 628 may comprise a resistor divider for generating a scaledvoltage (e.g., the voltage feedback signal V_(FB-V)). The controlcircuit 620 may receive the voltage measurement signal V_(FB-V) and maycalculate the amount of power presently being consumed by the driverand/or lighting load using the present magnitude of the line voltage andthe present magnitude of load current I_(LOAD) as measured by thecurrent measurement circuit 626.

The control module 600 further comprises a communication circuit 630,which may be similar to the communication circuits 430, 530 of the LEDdrivers 400, 500 shown in FIGS. 4 and 5. The communication circuit 630may be coupled to a digital communication link, for example, a wiredcommunication link or a wireless communication link, such as aradio-frequency (RF) communication link or an infrared (IR)communication link. The control circuit 620 may be configured totransmit and receive digital messages on the communication link via thecommunication circuit 630. The control module 600 may also comprise acommunication circuit 632 adapted to be coupled to one or more LEDdrivers via a fixture control link (e.g., the fixture control links 328,338 shown in FIG. 3). The control circuit 620 may be configured to usethe color engine stored in the memory 622 to control the LED driverscoupled to the communication circuit 632 in dependence upon a commandincluded in a single digital message received via the communicationcircuit 630.

FIG. 7 is a simplified flowchart of an example configuration procedure700 for configuring a multiple-driver lighting fixture having multipleLED light sources and respective LED drivers. For example, the LED lightsources may comprise different color LED light sources and the LEDdrivers may be configured to control the LED light sources to control anintensity, color, and/or color temperature of a cumulative light emittedby the multiple-driver lighting fixture. The configuration procedure 700may be executed at step 710, for example, using a configuration tool atan OEM. At step 712, the first LED driver to be installed in thelighting fixture may be first inserted into the configuration tool. Theconfiguration tool may assign a fixture serial number to the LED driverat step 714 (e.g., the same fixture serial number for each of the LEDdrivers in the lighting fixture), and may assign a unique sub-address tothe LED driver at step 716 (e.g., depending upon what color LED lightsource the LED driver is controlling). The configuration tool mayconfigure the LED driver with an appropriate light engine (e.g., colorengine) at step 718 depending upon the desired control technique for thelighting fixture (e.g., fixed color temperature, color trajectory, orcolor map). If there are more LED drivers to configure in the lightingfixture at step 720, the next LED driver may be installed in theconfiguration tool at step 722, and the procedure may loop around toassign the fixture serial number, a unique sub-address, and a colorengine to the next LED driver. When there are no more LED drivers in thelighting fixture to configure at step 720, the LED light sources and LEDdrivers may be installed in the lighting fixture at step 724 and thelighting fixture may be calibrated at step 726, before the configurationprocedure 700 ends at step 728.

FIG. 8 is a simplified flowchart of an example setup procedure 800 forprogramming the operation of a load control system havingmultiple-driver lighting fixtures (e.g., the load control system 200 ofFIG. 2). For example, the setup procedure 800 may be executed by asystem controller of the load control system (e.g., the systemcontroller 240). After the setup procedure 800 is initiated at step 810,the system controller may transmit a query message to a plurality of LEDdrivers on a digital communication link at step 812. The query messagemay request responses from LED drivers that are assigned a fixtureserial number (e.g., LED drivers that are installed in multiple-driverlighting fixtures). The response may include the fixture serial numberand/or corresponding driver serial numbers of the LED drivers thatreceived the query. If the system controller receives a response fromany of the LED drivers at step 814, the system controller may store thedriver serial numbers and corresponding fixture serial numbers in memoryat step 816.

The system controller may assign a link address to each of the LEDdrivers for identified fixtures. At step 818, the system controller mayselect one of the fixture serial numbers from which the systemcontroller received responses at step 814. The system controller maytransmit the next free link address to each of the LED drivers havingthe selected fixture serial number at step 820. If there are morefixture serial numbers stored in memory at step 822, the systemcontroller may select the next fixture serial number at step 824 andtransmit the next free link address to each of the LED drivers havingthat fixture serial number at step 820. If there are not more fixtureserial numbers at step 822, the system controller may transmit linkaddresses to each of the other LED drivers (e.g., a different linkaddress to each LED driver) at step 826, before the setup procedure 800exits at step 828.

FIG. 9 is a simplified flowchart of an example message processingprocedure 900, which may be executed by an LED driver (e.g., one of theLED drivers of the load control system 200 shown in FIG. 2). The messageprocessing procedure 900 may be executed by a control circuit of the LEDdriver when the LED driver receives a digital message via a digitalcommunication link at step 910. If the received digital message does notinclude the link address of the LED driver at step 912, the messageprocessing procedure 900 may simply exit at step 914. If the receiveddigital message includes the link address of the LED driver at step 910and the digital message includes a preset command (e.g., a parameterindicating for the LED driver to go-to a specific color temperature) atstep 916, the LED driver may determine the appropriate preset intensityfor the controlled LED light source using a light engine (e.g., a colorengine) stored in memory at step 918 and then control the intensity ofthe LED light source to that preset intensity at step 920, before themessage processing procedure 900 exits at step 914. If the receiveddigital message does not include a preset command at step 916, the LEDdriver may determine if the digital message includes the sub-address ofthe LED driver at step 922. If so, the LED driver may process thedigital message at step 924 and the message processing procedure 900 mayexit at step 914.

FIG. 10 is a simplified flowchart of another example message processingprocedure 1000, which may be executed by a control module (e.g., one ofthe control modules 326, 336 of the load control system 300 shown inFIG. 3). The message processing procedure 1000 may be executed by acontrol circuit of the control module when the control module receives adigital message via a digital communication link at step 1010. If thereceived digital message does not include the link address of thecontrol module at step 1012, the message processing procedure 1000 maysimply exit at step 1014. If the received digital message includes thelink address of the control module at step 1010 and the digital messageincludes a preset command (e.g., go-to a specific color temperature) atstep 1016, the control module may determine the appropriate presetintensities for each of the controlled LED light sources in the lightingfixture using a light engine (e.g., a color engine) stored in memory atstep 1018. The control module may then transmit a digital messageincluding the appropriate intensity to each of the LED light sources atstep 1020, before the message processing procedure 1000 exits at step1014. If the received digital message does not include a preset commandat step 1016, the control module may determine if the digital messageincludes the sub-address of one of the LED drivers in the lightingfixture at step 1022. If so, the control module may forward the digitalmessage onto the appropriate LED driver at step 1024 and the messageprocessing procedure 1000 may exit at step 1014.

FIG. 11 is a simplified flowchart of an example message processingprocedure 1100, which may be executed by a master LED driver (e.g., oneof the master LED drivers 424A, 434A of the load control system 400shown in FIG. 4). The message processing procedure 1100 may be executedby a control circuit of the master LED driver when the master LED driverreceives a digital message via a digital communication link at step1110. If the received digital message does not include the link addressof the control module at step 1112, the message processing procedure1100 may simply exit at step 1114. If the received digital messageincludes the link address of the master LED driver at step 1110 and thedigital message includes a preset command (e.g., a parameter indicatingfor the LED driver go-to a specific color temperature) at step 1116, themaster LED driver may determine the appropriate preset intensities foreach of the controlled LED light sources in the lighting fixture using alight engine (e.g., a color engine) stored in memory at step 1118. Themaster LED driver may control the intensity of the LED light sourcedirectly coupled to the master LED driver to the appropriate presetintensity at step 1120 and transmit a digital message including theappropriate intensity to each of the slave LED light sources at step1022, before the message processing procedure 1100 exits at step 1114.If the received digital message does not include a preset command atstep 1116, the master LED driver may determine if the digital messageincludes its sub-address at step 1124 or a sub-address of one of theslave LED drivers in the lighting fixture at step 1126. If the digitalmessage includes the sub-address of the master LED driver at step 1124,the master LED driver may process the digital message at step 1128 andthe message processing procedure 1100 may exit at step 1114. If thedigital message includes a sub-address of one of the slave LED driversin the lighting fixture at step 1126, the master LED driver may forwardthe digital message onto the appropriate LED driver at step 1130 and themessage processing procedure 1100 may exit at step 1114.

FIG. 12 is a block diagram illustrating an example system controller1200 as described herein. The system controller 1200 may include acontrol circuit 1202 for controlling the functionality of the systemcontroller 1200. The control circuit 1202 may include one or moregeneral purpose processors, special purpose processors, conventionalprocessors, digital signal processors (DSPs), microprocessors,integrated circuits, a programmable logic device (PLD), applicationspecific integrated circuits (ASICs), and/or the like. The controlcircuit 1202 may perform signal coding, data processing, power control,input/output processing, or any other functionality that enables thesystem controller 1200 to perform as described herein. The controlcircuit 1202 may store information in and/or retrieve information fromthe memory 1204. The memory 1204 may include a non-removable memoryand/or a removable memory. The non-removable memory may includerandom-access memory (RAM), read-only memory (ROM), a hard disk, or anyother type of non-removable memory storage. The removable memory mayinclude a subscriber identity module (SIM) card, a memory stick, amemory card, or any other type of removable memory.

The system controller 1200 may include a communications circuit 1206 fortransmitting and/or receiving information. The communications circuit1206 may perform wireless and/or wired communications. The systemcontroller 1200 may also, or alternatively, include a communicationscircuit 1208 for transmitting and/or receiving information. Thecommunications circuit 1206 may perform wireless and/or wiredcommunications. Communications circuits 1206 and 1208 may be incommunication with control circuit 1202. The communications circuits1206 and 1208 may include RF transceivers or other communicationsmodules capable of performing wireless communications via an antenna.The communications circuit 1206 and communications circuit 1208 may becapable of performing communications via the same communication channelsor different communication channels. For example, the communicationscircuit 1206 may be capable of communicating (e.g., with input devices,over a network, etc.) via a wireless communication channel (e.g.,BLUETOOTH®, near field communication (NFC), WIFI®, WI-MAX®, cellular,etc.) and the communications circuit 1208 may be capable ofcommunicating (e.g., with control devices and/or other devices in theload control system) via another wired or wireless communication channel(e.g., WI-FI® or a proprietary communication channel, such as CLEARCONNECT™).

The control circuit 1202 may be in communication with an LED indicator1212 for providing indications to a user. The control circuit 1202 maybe in communication with an actuator 1214 (e.g., one or more buttons)that may be actuated by a user to communicate user selections to thecontrol circuit 1202. For example, the actuator 1214 may be actuated toput the control circuit 1202 in an association mode and/or communicateassociation messages from the system controller 1200.

Each of the modules within the system controller 1200 may be powered bya power source 1210. The power source 1210 may include an AC powersupply or DC power supply, for example. The power source 1210 maygenerate a supply voltage V_(CC) for powering the modules within thesystem controller 1200.

FIG. 13 is a block diagram illustrating an example input device 1300 asdescribed herein. The input device 1300 may be a remote control device,an occupancy sensor, a daylight sensor, a window sensor, a temperaturesensor, and/or the like. The input device 1300 may include a controlcircuit 1302 for controlling the functionality of the input device 1300.The control circuit 1302 may include one or more general purposeprocessors, special purpose processors, conventional processors, digitalsignal processors (DSPs), microprocessors, integrated circuits, aprogrammable logic device (PLD), application specific integratedcircuits (ASICs), or the like. The control circuit 1302 may performsignal coding, data processing, power control, input/output processing,or any other functionality that enables the control-source device 1300to perform as described herein.

The control circuit 1302 may store information in and/or retrieveinformation from the memory 1304. The memory 1304 may include anon-removable memory and/or a removable memory, as described herein.

The input device 1300 may include a communications circuit 1308 fortransmitting and/or receiving information. The communications circuit1308 may transmit and/or receive information via wired and/or wirelesscommunications. The communications circuit 1308 may include atransmitter, an RF transceiver, or other circuit capable of performingwired and/or wireless communications. The communications circuit 1308may be in communication with control circuit 1302 for transmittingand/or receiving information.

The control circuit 1302 may also be in communication with an inputcircuit 1306. The input circuit 1306 may include an actuator (e.g., oneor more buttons) or a sensor circuit (e.g., an occupancy sensor circuit,a daylight sensor circuit, or a temperature sensor circuit) forreceiving input that may be sent to a device for controlling anelectrical load. For example, the control-source device may receiveinput from the input circuit 1306 to put the control circuit 1302 in anassociation mode and/or communicate association messages from thecontrol-source device. The control circuit 1302 may receive informationfrom the input circuit 1306 (e.g., an indication that a button has beenactuated or sensed information). Each of the modules within the inputdevice 1300 may be powered by a power source 1310.

Although features and elements are described herein in particularcombinations, each feature or element can be used alone or in anycombination with the other features and elements. The methods describedherein may be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), removable disks, and optical media such asCD-ROM disks, and digital versatile disks (DVDs).

What is claimed is:
 1. A lighting fixture having comprising: a pluralityof LED light sources; a plurality of LED drivers adapted to be coupledto a respective one of the LED light sources and configured to controlan intensity of the respective LED light source; and a control moduleconfigured to control the plurality of LED drivers to control anintensity and a color temperature of a cumulative light emitted by thelighting fixture, the control module configured to receive at least onedigital message for controlling the cumulative light emitted by theplurality of LED sources of the lighting fixture via a communicationlink; wherein the control module is further configured to control theintensity and the color temperature of the cumulative light emitted bythe lighting fixture according to one of a plurality of colortrajectories in response to a single digital message received via thecommunication link, wherein the single digital message includes adesired intensity for the cumulative light emitted by the lightingfixture and each of the plurality of color trajectories defines aplurality of color temperatures corresponding to a plurality ofrespective desired intensities.
 2. The lighting fixture of claim 1,wherein the control module comprises a control circuit configured to usea color engine to control the intensity and the color temperature of thecumulative light emitted by the lighting fixture according to the one ofthe plurality of color trajectories in response to the single digitalmessage received via the communication link.
 3. The lighting fixture ofclaim 2, wherein the control circuit is coupled to a first communicationcircuit for receiving the single digital message via the communicationlink.
 4. The lighting fixture of claim 3, wherein the control circuit iscoupled to a second communication circuit for transmitting digitalmessages to the plurality of LED drivers.
 5. The lighting fixture ofclaim 4, wherein the control circuit is configured to communicate withthe plurality of LED drivers using a respective sub-address of each ofthe LED drivers.
 6. The lighting fixture of claim 5, wherein the singledigital message received by the control circuit via the communicationlink includes a link address of the control module.
 7. The lightingfixture of claim 5, wherein the single digital message received by thecontrol circuit via the communication link includes a common linkaddress for the plurality of LED drivers in the lighting fixture.
 8. Thelighting fixture of claim 5, wherein the control circuit is configuredto assign the respective sub-addresses to the LED drivers during aconfiguration procedure of the lighting fixture.
 9. The lighting fixtureof claim 3, wherein the communication link comprises a wirelesscommunication link.
 10. The lighting fixture of claim 2, wherein thecontrol circuit is configured to store the plurality of colortrajectories in a memory.
 11. The lighting fixture of claim 1, whereinone or more of the plurality of color trajectories corresponds to acolor temperature of a known lamp as an intensity of the lamp isadjusted.
 12. The lighting fixture of claim 11, wherein the known lampcomprises at least one of an incandescent lamp, a halogen lamp, or afluorescent lamp.
 13. The lighting fixture of claim 1, wherein theplurality of LEDs are configured to emit light of different colors. 14.The lighting fixture of claim 13, wherein each of the LED driverscomprises a respective load regulation circuit configured to control anamount of power delivered to the respective LED light source to controlthe intensity of the LED light source.
 15. The lighting fixture of claim1, wherein the control module is configured to control the intensity ofthe cumulative light emitted by the lighting fixture towards the desiredintensity received in the signal digital message, and control the colortemperature of the cumulative light emitted by the lighting fixturetowards a color temperature determined from the desired intensity andthe one of the plurality of color trajectories.
 16. A method ofcontrolling a cumulative light emitted by a lighting fixture having aplurality of light-emitting diode (LED) light sources of differentcolors, the method comprising: controlling a plurality of LED drivers tocontrol respective intensities of each of the plurality of LED lightsources in order to control an intensity and a color temperature of thecumulative light emitted by the lighting fixture; receiving at least onedigital message for controlling the cumulative light emitted by theplurality of LED sources of the lighting fixture via a communicationlink; and controlling the intensity and the color temperature of thecumulative light emitted by the lighting fixture according to one of aplurality of color trajectories in response to a single digital messagereceived via the communication link; wherein the single digital messageincludes a desired intensity for the cumulative light emitted by thelighting fixture and each of the plurality of color trajectories definesa plurality of color temperatures corresponding to a plurality ofrespective desired intensities.
 17. The method of claim 16, furthercomprising: transmitting digital messages to the plurality of LEDdrivers using a respective sub-address of each of the LED drivers. 18.The method of claim 17, further comprising: assigning the respectivesub-addresses to the LED drivers during a configuration procedure of thelighting fixture.
 19. The method of claim 16, further comprising:storing the plurality of color trajectories in memory.
 20. The method ofclaim 16, further comprising: controlling the intensity of thecumulative light emitted by the lighting fixture towards the desiredintensity received in the signal digital message; and controlling thecolor temperature of the cumulative light emitted by the lightingfixture towards a color temperature determined from the desiredintensity and the one of the plurality of color trajectories.